Category Archives: Vaccines

Poster from before the 1979 eradication of smallpox, promoting vaccination. (Photo credit: Wikipedia)

Why is it that members of the public health community are worried about falling vaccination rates in the US when getting vaccinated is treated as a largely personal choice? Do our personal health decisions for ourselves and our children have an impact on the health of society as a whole?

The answer to this is that yes, our individual decisions do matter to society when it comes to combating the spread of contagious disease.

A large part of this is herd or community immunity; the way in which mass immunity in a population can control the spread of disease among individuals. Herd immunity is a major reason behind why so many deadly diseases have all but disappeared from American society; our vaccination rates protect many of those who are unvaccinated from contagious diseases. However, this is beginning to change in the US and we are beginning to see outbreaks of diseases that have not been of major clinical concern for decades.

How many people do you know who haven’t vaccinated their children out of fear of giving them autism or mercury poisoning?

Have you or do you plan to vaccinate your own children?

Where did this fear of vaccines come from and why does it persist despite vastly overwhelming data pointing to their safety?

Why are we suddenly seeing outbreaks of diseases such as measles and whooping cough, diseases that we had thought controlled in this country decades ago?

If you have ever thought about these questions go get a copy of The Panic Virus by Seth Mnookin and start reading. This is an incredibly well-researched volume not just on the science behind the vaccine-autism controversy, but on the swell of emotions and public opinion that have allowed this claim to bleed over into mainstream culture and persist despite volumes of rigorously peer-reviewed research debunking the myth time and again. The importance of this movement from a public health standpoint cannot be understated, in some parts of the country we are dangerously close to losing herd immunity to many pathogens due to falling vaccination rates. We are currently seeing outbreaks of diseases in the US that have been effectively gone for decades: measles, whooping cough, HiB, and other pathogens are coming back and hitting the growing unvaccinated populations in our country.

One of my very favorite aspects of being a scientist is being right on the cutting edge of modern research. I have the pleasure of working in an environment where new discoveries are made daily that span from the mundane to the revelatory. Today I want to take the time to write about a recent paper that for me came to my attention that falls solidly in the revelatory category.

Many of us are familiar with vaccines. In the US where I live most of us have been vaccinated for major diseases such as whooping cough, Hepatitis A, measles, mumps, rubella, tetanus, diphtheria, the list goes on. However, due to our developed infrastructure and relative ease of access to medical care many of us have never worried about obtaining vaccines for our children or ourselves. This alone has contributed to some of the most startling gains in public health that we’ve ever seen.

In other parts of the world though, this is a very different story. Less infrastructure and fewer opportunities for medical care has made vaccinating large segments of the human population extremely difficult with serious consequences for those who are not vaccinated.

One major hurdle in the race to vaccinate the majority of people on this planets is the maintenance of cold-chains for vaccine delivery.

It may surprise many of you to know that some vaccines currently being used are actually composed of a living virus that actively replicates in your body in order to generate immunity. I’ve written about one of these live vaccines before on this site: the oral polio vaccine (OPV). These are effective vaccines that mount a long-term adaptive immunity to the pathogen in question. This is done by immune cells that break down the virus and present small parts known as antigens to immature immune cells, which then mature in response to the antigen and are then capable of mounting an immune response to this same challenge in the future.

As we enter another autumn season the memories of summer begin to fade and our minds turn towards the impending winter as the leaves begin to crisp and fall. This time of year also marks the appearance of flu-shots and news stories about the newest and scariest strains of influenza virus. Recently, there have been multiple reports in the US about a new form of swine flu that has been circulating at county fairs as people and pigs enter close proximity (see Related Articles after the jump).

Why is a strain of flu that infects pigs or dangerous or even relevant for people? As it turns out, from the point of view of the influenza virus a pig, bird, or human are not terribly different. Furthermore, pigs are also susceptible to certain strains of bird flu just like humans and can be multiply infected with different strains that could be human, avian, or porcine in origin. What this means is that pigs are an ideal breeding ground for reassortant viruses and their subsequent antigenic shift, and this is where things get dangerous.